Unveiling the potential of plasmonic Ag/AgCl@Bi-MXene photocatalysts for selective NO removal

MXene-based photocatalysts have demonstrated excellent potential for the selective conversion of hazardous nitric oxide (NO). In this work, Ag/AgCl@Bi–MXene nanocomposites were successfully synthesized using a dual-etching-assisted strategy and systematically implemented for the photocatalytic NO removal. Characterization results confirmed the successful anchoring of Ag/AgCl nanoparticles and Bi incorporation onto MXene nanosheets, resulting in enhanced crystallinity and strong interfacial interactions. The photoluminescence (PL) and electron paramagnetic resonance (EPR) studies demonstrated suppressed charge recombination and surface defect states. Ag/AgCl nanoparticles on Mxene sheets can promote the formation of hot electrons and plasmonic effects, thereby favorably influencing the optical response. The optimized Ag/AgCl@Bi–MXene construction displayed 65.2% of NO removal in 10 min, substantially higher than Bi–MXene (38.6%), Ag/AgCl@MXene (51.4%), and pristine MXene (22.3%). Notably, NO₂ byproduct formation remained below 10 ppb, ensuring high selectivity. Quenching and electron spin resonance (ESR) experiments identified photogenerated electrons and O₂•- radicals as the dominant reactive species, supported by in-situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). Complementary density functional theory (DFT) calculations revealed bandgap alteration, an increased density of states near the Fermi level, and metallic-like behavior induced by Bi and Ag/AgCl, which corroborates the dual plasmonic enhancement and efficient ohmic contact at the Bi–MXene/AgCl interface. These synergistic effects collectively enable superior charge separation, directional electron transport, and light harvesting, establishing Ag/AgCl@Bi–MXene as a promising photocatalyst for light-driven NO abatement.